Re: [PATCH 1/2] x86-32: Fix crashes with CPU hotplug on AMDmachines

[Borislav Petkov]

From: "H. Peter Anvin" <hpa@xxxxxxxxx>
Date: Thu, Aug 12, 2010 at 11:34:37AM -0400

> On 08/12/2010 07:41 AM, Joerg Roedel wrote:
> > On Thu, Aug 05, 2010 at 07:14:14AM -0700, H. Peter Anvin wrote:
> >> On 08/05/2010 12:45 AM, Roedel, Joerg wrote:
> >> Correct, again.  It's unclear to me if we can get away with the very
> >> simple 64-bit approach -- in particular, not including all the 1:1
> >> mappings in the kernel -- for all future users, though.
> > 
> > Yeah, We could probably use the same symbol names for the trampoline and
> > the swapper page-table on 32 and 64 bit and merge the code that handles
> > it between the architectures. Shouldn't be too difficult. We cook
> > something up :-)
> > But do you mind to take this patch first? It fixes the occurence of an
> > erratum on AMD hardware, it is a quite simple fix compared to the rework
> > suggested. In fact, I would like to have a simple patch to fix the
> > problem first (and backport it as necessary) and then go the way to
> > rework the current code differences between 32 and 64 bit.
> > 
> 
> Agreed.  I do have a concern about the kernel page tables not being
> synchronized into trampoline_pg_dir (it's only an issue for 32-bit
> !PAE), so at the very least we need to keep an eye out for it...

I've been working on what you suggested and the patch boots on a 32-bit
PAE kernel but keeps rebooting on non-PAE after setting the stack_start
on the AP. I could send it out later for you to look at, if you like -
you should be able to spot what I'm missing :)...

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Regards/Gruss,
Boris.

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